1. Technical Field
One or more aspects according to embodiments of the present invention relate to organic light-emitting compounds and organic light-emitting devices including the organic light-emitting compounds, for example, anthracene derivatives and organic light-emitting devices including the anthracene derivatives.
2. Description of the Related Art
In an organic light-emitting device, materials used for an organic material layer may be categorized into an emission material or a charge-transporting material, depending on the function of the material used. Examples of charge-transporting materials include a hole-injecting material, a hole-transporting material, an electron-transporting material, and an electron-injecting material. The emission material may be categorized into a polymer-type or a low molecular weight type, depending on a molecular weight thereof. The emission material may be further categorized into a fluorescent material (e.g., a material having a singlet excited state of an electron) or a phosphorescent material (e.g., a material having a triplet excited state of an electron), depending on the emission mechanism thereof. Also, the emission material may be categorized into yellow or orange emission materials, depending on the color emitted, which are used to achieve more natural colors than blue, green, and red emission materials.
Meanwhile, when only one material is used as the emission material, problems, such as the occurrence of a molecular interaction, which causes a movement of a maximum emission wavelength as long-wavelength (e.g., a shift to a longer wavelength), decreased color purity, or decreased emission, may occur which reduce the efficiency of a device. Thus, a host-dopant system may be used for the emission material to improve emission efficiency through improved energy transfer and to increase color purity.
When a small amount of a dopant having a smaller energy band gap than a host of the emission layer is mixed into the emission layer, excitons generated in the emission layer are transported to the dopant to emit high efficiency light. In this regard, a wavelength of the host moves (or shifts) according to a wavelength of the dopant and thus, light of a desired wavelength may be obtained according to the type of the dopant.
For an organic light-emitting device to show good characteristics as described above, materials included in the organic material layer of the device, such as a hole-injecting material, a hole-transporting material, an emission material, an electron-transporting material, and/or an electron-injecting material need to be stable and efficient materials; however, there has not been sufficient development of a stable and efficient material for the organic material layer of the organic light-emitting device. Accordingly, development of a new material is continuously being pursued in the art.
For example, a phenanthryl anthracene derivative can be used as a host material. Such anthracene derivative can be used as a blue emission material; however, a driving voltage of the device using such an anthracene derivative needs to be improved. Also, a compound in which an anthracene ring and a naphthyl ring are directly connected can be used in a light-emitting device; however, lifespan characteristics of a device using the compound need to be improved for the commercialization thereof. Accordingly, there is a need to develop a good material for low driving voltage, improved emission efficiency, and long lifespan characteristics of an organic light-emitting device.